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A
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Changes off temperature and state
The two extracts below are from a basic
technical training course for the customer service staff of a manufacturer
of heating boilers.
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As you know, temperature is
measured in degrees Celsius (0C). But heat is energy, so it’s
measured in Joules. To calculate the amount of energy needed to raise the
temperature of a substance, you need to know the mass of the substance
being heated, and also its specific heat capacity – in other words, the
amount of energy, in joules, required to raise the temperature of one kilogram
of the substance by one degree Celsius.
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B
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Heat transfer
The textbook
extract below looks at heat transfer – how heat travels.
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To help understand heat
transfer, homes provide everyday examples. The heating systems in homes
often have electric convertor heaters. These heat the air and make it
circulate, so that it moves in a circle – first rising, then cooling and
sinking before rising again. This is called convection, where warm gas or
liquid moves around and dissipates heat, transferring it to the rest of
the gas or liquid.
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EXERCISES
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36.1
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Complete the sentences about water using words from A opposite. Sometimes
there is more than one possible answer.
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1. When the temperature of
the ice reaches 0˚C, it changes __________ - it __________ to become water.
2. At 100˚C, water __________.
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36.2
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Match the two
parts to make correct sentences. Look at A and B opposite, and appendix VII
to help you.
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1. A liquid pumped onto a
workpiece that is being machined, to stop it overheating, is called a
2. The form of heat transfer
that occurs with infrared heat – a form of electromagnetic wave – is called
3. The metal fins (plates) around
air-cooled engines, intended to maximize the surface area of the hot
engine that is in contact with the cooler air, are designed to act as a
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36.3
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Circle the correct words to
complete the article about condensing boilers. Look at A and B opposite to
help you. The first one has been done for you.
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Condensing boilers are
becoming increasingly popular in homes, as they use up to 40% less gas than
traditional boilers. How do they work? By exploiting the fact that when a
liquid condenses, due to the principle of latent heat of (1) fusion/ vaporization, the process
is (2) endothermic/ exothermic.
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